Long arm cast

These fractures are often displaced and unstable and should not be treated with simple splintage. However, if the fracture is undisplaced or minimally displaced, casting is sufficient.

The purpose of the cast is to stabilize the fracture in addition to providing symptomatic relief during the period of fracture healing.

Although there is no convincing evidence, comminuted metaphyseal fractures are often unstable and application of a long arm cast controls forearm rotation, and at least from a theoretical perspective, will decrease the risk of displacement.

The long arm cast is applied according to standard procedure:

• Long arm cast

If a complete cast is applied in the acute phase after injury, it is safer to split the cast down to skin over its full length.

Further swelling in a restricting cast can cause pain, venous congestion in the fingers and occasionally a compartment syndrome.

For this reason any complete cast applied in acute phase should be split down to skin.

Parents/carers should be instructed how to detect circulatory problems by pressing and releasing the fingertips and watching if the blood flow/color returns to normal (capillary refill), compared to the opposite hand.

Compartment syndrome is an unusual but serious complication after the application of a complete cast and can be difficult to diagnose, especially in younger children. Neurological signs appear late and the main sign is excessive pain on passive extension of the fingers.

It is important to make sure that the parents/carers are aware of the risk of compartment syndrome.

The parents/carers and patient should be informed to take note of increased pain and/or unresponsiveness to normal painkillers.

They should know that this may indicate serious complications. It is important for them to detect these signs as early as possible and report them urgently to the surgeon/nurse by telephone, or to attend the Emergency Room (ER) without delay.

Nerve compression is an occasional complication and the signs include:

• Sensory deficits (numbness)
• Weakness of active finger movement
• Paresthesia (tingling)

If a normal plaster of Paris cast is used, it is important to keep the cast clean and dry in order to maintain the reduction.

When the swelling has reduced, the cast can become loose. The loss of support can result in loss of reduction.

In this circumstance, the parents/carers are advised to return to the healthcare provider.

Depending on the fracture pattern, the age of the child and the method of treatment, the patient has to return for follow-up x-rays to monitor the fracture position.

X-rays taken for fracture position can be taken with cast in place. Any x-rays to assess the state of bone healing must be taken without the cast and correlated with clinical examination.

In most cases, it is conventional to obtain follow-up x-rays after reduction to ensure that the position is maintained.

In general, in the child below 5 years of age, the follow-up is usually about 4-5 days after reduction. In the older child with a potentially unstable fracture, an x-ray would normally be taken at 7-10 days.

Further follow-up x-ray is a matter of clinical judgement, the responsibility of the treating surgeon, and tends to be longer in older children.

For complete fractures of the metaphysis, redisplacement after reduction is not uncommon. It is therefore, important to take early follow-up x-rays in order to detect a possible redisplacement.